Several antibiotics of the cephalosporin class have achieved an important status in the treatment and control of infectious diseases of man. For example, the well known cephalosporin antibiotics, cephalothin, cephaloglycin, cephaloridine, and cephalexin have been widely used in the treatment of infections in man. Considerable effort continues to be extended in the development of new cephalosporin antibiotics with increased antibiotic activity and particularly with an expanded spectrum of activity against the gram-negative microorganisms.